Eighteen children were killed when a train crashed into their school bus at an unmanned railway crossing in southern India, police said.

The bus driver also died, while another 20 children aged seven to 14 were injured, 15 critically.

They were on their way to school when the train hit the bus, dragging it several hundred feet along the tracks, according to the Hindustan Times newspaper.

Hundreds of villagers rushed to the scene in Medak district, 60 miles north of Hyderabad, the capital of Telangana state. Some of them hurled stones at police as shocked parents grieved for their loss.

A father who lost both of his children suffered a heart attack and died after hearing the news of the collision, said state Irrigation Minister T Harish Rao.

Accidents are common on India's rail network, one of the world's largest with 23 million people riding daily on about 11,000 passenger trains. Most accidents are blamed on poor maintenance and human error.

There are hundreds of unmanned crossings across the country, especially in remote areas. Poor finances limit efforts by rail authorities to staff the dangerous crossings around the clock.